We're working on live public transport schedules as the first step to public transport routing. Here is the helper web app that shows currently supported GTFS feeds in different countries and cities and helps to match bus/tram/train stops from OpenStreetMap.org with stops from GTFS: https://gtfs-osm-matcher.organicmaps.app/
If you are interested in public transport schedules in your city, please let us know about feeds for your place/country, and help by adding/editing stops in OpenStreetMap.org
@organicmaps Is there a manual available? I'm happy to help, and I frequently edit OpenStreetMap, but I'm unfamiliar with how GTFS is supposed to work.
@cimm working on it. Any feedback is welcome. Check the web app, it highlights non-matched PT stops.
@organicmaps According to the OSM's wiki it seems I need to add gtfs:stop_id, gtfs:stop_name and uic_ref tags to the station node. The values can be found in the GTFS feeds (which I found via TransitLand). Easy enough!
GTFS - OpenStreetMap Wiki

@cimm right! Note that there could be more than one feed in some cases for different transport agencies.